Harry Potter and the Catalyst of Time
by FlyingLuna
Summary: The Death Eaters have surrounded Number Twelve, Grimmauld Place, leaving Harry and his remaining friends with no hope of escape. Harry must go back in time, carefully using his future knowledge to save the past, but will he lose more than he gains?


Disclaimer: I don't own Harry Potter! The lovely J. K. Rowling does.

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Chapter 1

_BANG!_

The paintings grumbled unhappily at being so harshly woken from their slumber, but the inhabitants of Number Twelve, Grimmauld Place, paid them no mind. The clock struck two just as a second _BANG!_ followed the first.

"Can't they let us sleep anymore? At least wait until morning?" a tired Harry Potter asked no one in particular as he exited Sirius's – now his – bedroom.

"That would be more convenient for you, so naturally they're not about to do that," Severus reminded him. "It's their orders to attack us when they think we will be most unprepared."

"It's rude, that's what it is," Harry muttered.

"They're getting closer to breaking through the wards," Tonks informed them, having come upstairs from her post just inside the front door. She had served as their guard that night, keeping an eye out for any advances the regiment of Death Eaters outside their door should make. If they got in, she would, at best, be able to serve as a distraction so the rest could get somewhere safe.

Or so they hoped.

"It has to be today, then," Harry said firmly.

"But Harry, we don't even know if the spell is _ready_ yet!"

"Tonks, I've run through the theory a hundred times in the last week. It's as ready as it's ever going to be."

Soft footsteps echoed from Harry's room, and Draco slid quietly into the hallway. "Why is everyone up so bloody early?" he moaned.

"I don't know how you could have possibly slept through two attacks on the wards," Severus said incredulously.

"_Two?_ Are they still holding?" Draco asked, suddenly concerned at the state of Grimmauld Place. He glanced worriedly at the walls and ceiling as if they could fall in at any second.

"They're okay for now," Harry answered, trying to alleviate Draco's fear, "but we need to do the spell today."

Draco blanched. "_What?!" _he shouted, suddenly completely alert to the situation. "No. There is no _way_ you're leaving me, not this soon-"

Harry cut off Draco's protests by wrapping his arms around the blonde-haired boy's shoulders. "Draco, it has to be today," he whispered. Draco buried his head into Harry's shoulder.

"But why?" he asked pitifully.

"Things will be better this way."

Tonks and Severus averted their gazes from the two 20-year-old boys. Severus turned towards the stairs, grabbing the shoulder of Tonks' robe and pulling her downstairs with him. "Let's give them a minute," Severus murmured once they were out of hearing range.

"I don't know who I feel worse for – Harry or Draco? Granted, Harry will find a different Draco in the past, but it won't be nearly the same…" Tonks mused. She could have sworn she heard Severus mutter, "We'll see about that," but she decided it was a figment of her imagination.

"So what do we do now?" Severus asked after a moment of silence.

"We get ready to say goodbye."

"And then?"

"We brace ourselves." Both understood the meaning behind those simple words: they wouldn't stand a chance. Their goodbyes would be not just with Harry but with each other.

Hours later, Severus sat at the kitchen table, scowling over a stack of parchment. He was going over the power requirements and theory behind the spell once again – if Harry had done it a hundred times, Severus must have done it a thousand. He dreaded using the spell, but knew it was necessary. Still, he didn't want to send Harry back to the wrong time, or worse, have him disappear completely.

"Are you _still_ pouring over those pages?" Harry's voice startled Severus from his work; if anything, his scowl became more pronounced.

"You seem to be under the misapprehension that nothing can go wrong. While I understand you were sorted into _Gryffindor_, and as such, are prone to idiotic fits of bravery, _I _prefer not to take any chances with your life and our magic."

"Severus, I'm just as paranoid as you are," Harry replied. "However, I prefer to spend my last few hours with my friends doing something other than staring at a piece of parchment." Severus frowned; although he and Harry had become – dare he admit it – _friends _over the last few years, they had a very strained relationship. Neither of them wished to be overly emotional with the other.

And Harry had essentially just admitted he wanted to spend time with him.

"Becoming sentimental now, are you, Potter?"

"More like preparing for a world where I won't see you three for a while, if ever," said Harry.

"Is that your way of saying you'll miss me?" Severus asked. Harry looked down in embarrassment. "Well, since chances are I'll never see _this_ you again, I see no harm in telling you that I will miss you as well, Harry." Severus placed a comforting hand on the boy's shoulder before continuing. "You'll be fine. You're Harry-Bloody-Potter, the Boy-Who-Lived. You've proven me wrong time and time again; I have no doubt that you will continue to do so in the past."

"I'd rather just be Harry-Bloody-Potter instead of some hero," Harry grumbled. He glanced up to see Severus's almost smiling face.

"Well, we all have our own burdens. Yours just so happens to be larger than most."

"The size of a dragon is more like it," Harry muttered. He sighed. "Severus, I- well, I mean, I just want to thank you, sir. For everything."

"You are most welcome, Mr. Potter. I could say the same to you." Both were silent; Harry was desperately trying to commit _this_ Snape to his memory before he went back to a time where he was hated by him. Severus cleared his throat. "We'll have to do this sooner rather than later," Severus told Harry.

"I know. How much longer do I have here?" Harry asked, dreading the answer.

"Not long, perhaps an hour or two. I suggest you make the most of it." Harry nodded, the reality of the situation catching up to him and causing his mood to drastically fall. He turned and was about to leave the kitchen when Severus stopped him.

"Harry?" Severus called, making him freeze mid-step. "Your parents would have been so proud of you." Suddenly, despite the difficulty Harry knew he would face in his future – well, past, as it was – he knew it would most definitely be worth it.

One hour later, Severus, Tonks, Harry, and Draco were standing in the front hallway. A circle along with the necessary runes had been drawn in chalk on the hardwood floor. Each person was depositing objects into a small bag which had an Undetectable Extension Charm placed on it.

"Here is the journal," said Severus. "I have included a memory to make my past self, whenever it is you arrive, believe your story." Harry nodded, preparing to slip the book into the bag. "However, Harry, you _must_ befriend my past self before you can show him. Otherwise, he will think it is all a trick. The earlier you arrive in the timeline, the easier it will be to befriend him – _me_."

"I will, Severus. I won't fail," Harry vowed. He closed the bag, the book safely tucked inside.

Tonks wrapped her arms around Harry. "I'm going to miss you," she whispered.

"You won't have time to miss me," Harry responded miserably. "As soon as I'm gone, you all won't stand a chance," he reminded them sadly.

"It'll be worth it in the end," Tonks told him. She let go of him and shook her head. "Take care of yourself, Harry. Don't forget to find me in the future. Hopefully, we'll be friends sooner than in this time."

"Don't worry; I couldn't have gotten this far without you, Tonks." Tonks nodded, tears in her eyes; in her sadness, her hair turned from its usual bubblegum pink to a more subdued dusty rose color.

"Harry." He turned to look at Draco, the blonde's eyes reflecting his misery. Harry's last goodbye would be the hardest. "I…I don't want you to go," he whispered. "I might never see you again."

"Don't worry," Harry reassured him. "We'll meet again. Things have a way of happening, even when you least expect it," he said, remembering similar words Luna said to him shortly after Sirius had passed away. Draco pulled Harry into a strong hug, kissing him quickly before letting him go for the last time.

"Now, Harry," Severus began, "when you return, you will have 24 hours to find your counterpart. You will merge into his body, and you will take over his memories. He will, for all intents and purposes, cease to exist. Your magic will merge with his as well."

"Severus," Harry interrupted, "I know all of this already." He was met with the stern glare of the Potions Master.

"Be that as it may, I am telling you yet _again_ to ensure this plan goes perfectly. We only have one chance to get this right." Harry nodded and allowed Severus to continue. "Any objects you want to bring with you must be on your person when we send you back."

"Is that all, Severus?" asked Tonks.

"I believe so. You all know the words of the spell?" Severus confirmed one last time. Once he saw the other three nod in confirmation, he continued. "Then we must begin." He directed Harry to stand inside the chalk circle, while Severus, Tonks, and Draco moved to three points equidistant from each other around the outside of the design.

Harry nodded that he was ready, and, as one, they intoned the spell: "Tempore reverteris ad catalyst."

In seconds, Harry was trapped in a vortex of wind and magic as the spell took hold of him. He could hear screaming; he was not entirely sure if it was Tonks, Severus, and Draco screaming as their magic was completely pulled from them or his own screams he was surrounded by the raw magic.

Over the noise, he could not hear Severus's parting words: "Do _not_ let yourself be seen!" Even more heart wrenching was Draco's shouting, something he had never said to Harry before, and something Harry would not be able to hear: "Damn it, Harry, I love you!"

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For a moment, Harry was not sure if the spell had worked; he was still standing in the middle of Number Twelve, Grimmauld Place, but upon closer inspection, he noticed things were very different from the timeline he had just left. For starters, Tonks, Severus, and Draco were no longer standing around him. The painting of Walburga Black was once again mounted to the wall, shrieking about half bloods and mudblood. And lastly, the most notable change of all: Sirius Black was standing in front of him.

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_Author's Note:_ I don't by any means know Latin. I will freely admit that I used Google Translate to make the spell, so take its translation with a grain of salt. I'll say now that if anything seems similar to another story, it was not done intentionally. Time travel fics are my favorite, so I have read a ton over the years, although I am trying to make mine as different as possible!

Any reviews would be highly appreciated! I have only just begun this story, although I have outlined a few chapters, so if there is something you would like to see Harry do in the past, please let me know! Also, if there are any questions, feel free to ask those as well!


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